void Wire::delay_optimal_wire() {
double len = wire_length;
//double min_wire_width = wire_width; //m
double beta = pmos_to_nmos_sz_ratio();
double switching = 0; // switching energy
double short_ckt = 0; // short-circuit energy
double tc = 0; // time constant
// input cap of min sized driver
double input_cap = gate_C(g_tp.min_w_nmos_ + min_w_pmos, 0);
// output parasitic capacitance of
// the min. sized driver
double out_cap = drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def);
// drive resistance
double out_res = (tr_R_on(g_tp.min_w_nmos_, NCH, 1) + tr_R_on(min_w_pmos, PCH, 1)) / 2;
double wr = wire_res(len); //ohm
// wire cap /m
double wc = wire_cap(len);
// size the repeater such that the delay of the wire is minimum
double repeater_scaling = sqrt(out_res * wc / (wr * input_cap)); // len will cancel
// calc the optimum spacing between the repeaters (m)
repeater_spacing = sqrt(2 * out_res * (out_cap + input_cap) / ((wr / len) * (wc / len)));
repeater_size = repeater_scaling;
switching = (repeater_scaling * (input_cap + out_cap) + repeater_spacing * (wc / len)) * deviceType->Vdd *
deviceType->Vdd;
tc = out_res * (input_cap + out_cap) + out_res * wc / len * repeater_spacing / repeater_scaling +
wr / len * repeater_spacing * input_cap * repeater_scaling +
0.5 * (wr / len) * (wc / len) * repeater_spacing * repeater_spacing;
delay = 0.693 * tc * len / repeater_spacing;
#define Ishort_ckt 65e-6 /* across all tech Ref:Banerjee et al. {IEEE TED} */
short_ckt = deviceType->Vdd * g_tp.min_w_nmos_ * Ishort_ckt * 1.0986 * repeater_scaling * tc;
area.set_area((len / repeater_spacing) *
compute_gate_area(INV, 1, min_w_pmos * repeater_scaling, g_tp.min_w_nmos_ * repeater_scaling,
g_tp.cell_h_def));
power.readOp.dynamic = ((len / repeater_spacing) * (switching + short_ckt));
power.readOp.leakage = ((len / repeater_spacing) * (1 + beta) / 2 * deviceType->Vdd * deviceType->I_off_n *
g_tp.min_w_nmos_ * repeater_scaling);
}
// nand gate sizing calculation
void Htree2::input_nand(double s1, double s2, double l_eff)
{
Wire w1(wt, l_eff);
double pton_size = deviceType->n_to_p_eff_curr_drv_ratio;
// input capacitance of a repeater = input capacitance of nand.
double nsize = s1*(1 + pton_size)/(2 + pton_size);
nsize = (nsize < 1) ? 1 : nsize;
double tc = 2*tr_R_on(nsize*min_w_nmos, NCH, 1) *
(drain_C_(nsize*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)*2 +
2 * gate_C(s2*(min_w_nmos + min_w_pmos), 0));
delay+= horowitz (w1.out_rise_time, tc,
deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, RISE);
power.readOp.dynamic += 0.5 *
(2*drain_C_(pton_size * nsize*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+ drain_C_(nsize*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+ 2*gate_C(s2*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd;
power.searchOp.dynamic += 0.5 *
(2*drain_C_(pton_size * nsize*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+ drain_C_(nsize*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+ 2*gate_C(s2*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd * wire_bw ;
power.readOp.leakage += (wire_bw*cmos_Isub_leakage(min_w_nmos*(nsize*2), min_w_pmos * nsize * 2, 2, nand))*deviceType->Vdd;
power.readOp.gate_leakage += (wire_bw*cmos_Ig_leakage(min_w_nmos*(nsize*2), min_w_pmos * nsize * 2, 2, nand))*deviceType->Vdd;
}
powerDef Wire::wire_model(double space, double size, double* delay) {
powerDef ptemp;
double len = 1;
//double min_wire_width = wire_width; //m
double beta = pmos_to_nmos_sz_ratio();
// switching energy
double switching = 0;
// short-circuit energy
double short_ckt = 0;
// time constant
double tc = 0;
// input cap of min sized driver
double input_cap = gate_C(g_tp.min_w_nmos_ + min_w_pmos, 0);
// output parasitic capacitance of
// the min. sized driver
double out_cap = drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def);
// drive resistance
double out_res = (tr_R_on(g_tp.min_w_nmos_, NCH, 1) + tr_R_on(min_w_pmos, PCH, 1)) / 2;
double wr = wire_res(len); //ohm
// wire cap /m
double wc = wire_cap(len);
repeater_spacing = space;
repeater_size = size;
switching = (repeater_size * (input_cap + out_cap) + repeater_spacing * (wc / len)) * deviceType->Vdd *
deviceType->Vdd;
tc = out_res * (input_cap + out_cap) + out_res * wc / len * repeater_spacing / repeater_size +
wr / len * repeater_spacing * out_cap * repeater_size +
0.5 * (wr / len) * (wc / len) * repeater_spacing * repeater_spacing;
*delay = 0.693 * tc * len / repeater_spacing;
#define Ishort_ckt 65e-6 /* across all tech Ref:Banerjee et al. {IEEE TED} */
short_ckt = deviceType->Vdd * g_tp.min_w_nmos_ * Ishort_ckt * 1.0986 * repeater_size * tc;
ptemp.readOp.dynamic = ((len / repeater_spacing) * (switching + short_ckt));
ptemp.readOp.leakage = ((len / repeater_spacing) * (1 + beta) / 2 * deviceType->Vdd * deviceType->I_off_n *
g_tp.min_w_nmos_ * repeater_size);
return ptemp;
}
double Wire::signal_rise_time() {
/* rise time of inverter 1's output */
double ft;
/* fall time of inverter 2's output */
double rt;
double timeconst;
timeconst =
(drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) + drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) * tr_R_on(g_tp.min_w_nmos_, NCH, 1);
rt = horowitz(0, timeconst, deviceType->Vth / deviceType->Vdd, deviceType->Vth / deviceType->Vdd, RISE) /
deviceType->Vth;
timeconst =
(drain_C_(g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) + drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
gate_C(min_w_pmos + g_tp.min_w_nmos_, 0)) * tr_R_on(min_w_pmos, PCH, 1);
ft = horowitz(rt, timeconst, deviceType->Vth / deviceType->Vdd, deviceType->Vth / deviceType->Vdd, FALL) /
(deviceType->Vdd - deviceType->Vth);
return ft; //sec
}
/*
* Calculates the delay, power and area of the transmitter circuit.
*
* The transmitter delay is the sum of nand gate delay, inverter delay
* low swing nmos delay, and the wire delay
* (ref: Technical report 6)
*/
void
Wire::low_swing_model() {
double len = wire_length;
double beta = pmos_to_nmos_sz_ratio();
double inputrise = (in_rise_time == 0) ? signal_rise_time() : in_rise_time;
/* Final nmos low swing driver size calculation:
* Try to size the driver such that the delay
* is less than 8FO4.
* If the driver size is greater than
* the max allowable size, assume max size for the driver.
* In either case, recalculate the delay using
* the final driver size assuming slow input with
* finite rise time instead of ideal step input
*
* (ref: Technical report 6)
*/
double cwire = wire_cap(len); /* load capacitance */
double rwire = wire_res(len);
#define RES_ADJ (8.6) // Increase in resistance due to low driving vol.
double driver_res = (-8 * g_tp.FO4 / (log(0.5) * cwire)) / RES_ADJ;
double nsize = R_to_w(driver_res, NCH);
nsize = MIN(nsize, g_tp.max_w_nmos_);
nsize = MAX(nsize, g_tp.min_w_nmos_);
if (rwire * cwire > 8 * g_tp.FO4) {
nsize = g_tp.max_w_nmos_;
}
// size the inverter appropriately to minimize the transmitter delay
// Note - In order to minimize leakage, we are not adding a set of inverters to
// bring down delay. Instead, we are sizing the single gate
// based on the logical effort.
double st_eff = sqrt(
(2 + beta / 1 + beta) * gate_C(nsize, 0) / (gate_C(2 * g_tp.min_w_nmos_, 0) + gate_C(2 * min_w_pmos, 0)));
double req_cin = ((2 + beta / 1 + beta) * gate_C(nsize, 0)) / st_eff;
double inv_size = req_cin / (gate_C(min_w_pmos, 0) + gate_C(g_tp.min_w_nmos_, 0));
inv_size = MAX(inv_size, 1);
/* nand gate delay */
double res_eq = (2 * tr_R_on(g_tp.min_w_nmos_, NCH, 1));
double cap_eq = 2 * drain_C_(min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(2 * g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) +
gate_C(inv_size * g_tp.min_w_nmos_, 0) + gate_C(inv_size * min_w_pmos, 0);
double timeconst = res_eq * cap_eq;
delay = horowitz(inputrise, timeconst, deviceType->Vth / deviceType->Vdd, deviceType->Vth / deviceType->Vdd, RISE);
double temp_power = cap_eq * deviceType->Vdd * deviceType->Vdd;
inputrise = delay / (deviceType->Vdd - deviceType->Vth); /* for the next stage */
/* Inverter delay:
* The load capacitance of this inv depends on
* the gate capacitance of the final stage nmos
* transistor which in turn depends on nsize
*/
res_eq = tr_R_on(inv_size * min_w_pmos, PCH, 1);
cap_eq = drain_C_(inv_size * min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(inv_size * g_tp.min_w_nmos_, NCH, 1, 1, g_tp.cell_h_def) + gate_C(nsize, 0);
timeconst = res_eq * cap_eq;
delay += horowitz(inputrise, timeconst, deviceType->Vth / deviceType->Vdd, deviceType->Vth / deviceType->Vdd, FALL);
temp_power += cap_eq * deviceType->Vdd * deviceType->Vdd;
transmitter.delay = delay;
transmitter.power.readOp.dynamic = temp_power * 2; /* since it is a diff. model*/
transmitter.power.readOp.leakage = 0.5 * deviceType->Vdd *
(4 * cmos_Ileak(g_tp.min_w_nmos_, min_w_pmos, g_ip->temp) *
NAND2_LEAK_STACK_FACTOR +
4 * cmos_Ileak(g_tp.min_w_nmos_, g_tp.min_w_nmos_, g_ip->temp));
inputrise = delay / deviceType->Vth;
/* nmos delay + wire delay */
cap_eq = cwire + drain_C_(nsize, NCH, 1, 1, g_tp.cell_h_def) * 2 + nsense * sense_amp_input_cap(); //+receiver cap
/*
* NOTE: nmos is used as both pull up and pull down transistor
* in the transmitter. This is because for low voltage swing, drive
* resistance of nmos is less than pmos
* (for a detailed graph ref: On-Chip Wires: Scaling and Efficiency)
*/
timeconst = (tr_R_on(nsize, NCH, 1) * RES_ADJ) * (cwire + drain_C_(nsize, NCH, 1, 1, g_tp.cell_h_def) * 2) +
rwire * cwire / 2 + (tr_R_on(nsize, NCH, 1) * RES_ADJ + rwire) * nsense * sense_amp_input_cap();
/*
* since we are pre-equalizing and overdriving the low
* swing wires, the net time constant is less
* than the actual value
*/
delay += horowitz(inputrise, timeconst, deviceType->Vth / deviceType->Vdd, .25, 0);
#define VOL_SWING .1
temp_power += cap_eq * VOL_SWING * .400; /* .4v is the over drive voltage */
temp_power *= 2; /* differential wire */
l_wire.delay = delay - transmitter.delay;
l_wire.power.readOp.dynamic = temp_power - transmitter.power.readOp.dynamic;
l_wire.power.readOp.leakage = 0.5 * deviceType->Vdd * (4 * simplified_nmos_leakage(nsize, g_ip->temp));
//double rt = horowitz(inputrise, timeconst, deviceType->Vth/deviceType->Vdd,
// deviceType->Vth/deviceType->Vdd, RISE)/deviceType->Vth;
delay += g_tp.sense_delay;
sense_amp.delay = g_tp.sense_delay;
out_rise_time = g_tp.sense_delay / (deviceType->Vth);
sense_amp.power.readOp.dynamic = g_tp.sense_dy_power;
sense_amp.power.readOp.leakage = 0; //FIXME
power.readOp.dynamic = temp_power + sense_amp.power.readOp.dynamic;
power.readOp.leakage = transmitter.power.readOp.leakage + l_wire.power.readOp.leakage +
sense_amp.power.readOp.leakage;
}
// tristate buffer model consisting of not, nand, nor, and driver transistors
void Htree2::output_buffer(double s1, double s2, double l_eff)
{
Wire w1(wt, l_eff);
double pton_size = deviceType->n_to_p_eff_curr_drv_ratio;
// input capacitance of repeater = input capacitance of nand + nor.
double size = s1*(1 + pton_size)/(2 + pton_size + 1 + 2*pton_size);
double s_eff = //stage eff of a repeater in a wire
(gate_C(s2*(min_w_nmos + min_w_pmos), 0) + w1.wire_cap(l_eff*1e-6))/
gate_C(s2*(min_w_nmos + min_w_pmos), 0);
double tr_size = gate_C(s1*(min_w_nmos + min_w_pmos), 0) * 1/2/(s_eff*gate_C(min_w_pmos, 0));
size = (size < 1) ? 1 : size;
double res_nor = 2*tr_R_on(size*min_w_pmos, PCH, 1);
double res_ptrans = tr_R_on(tr_size*min_w_nmos, NCH, 1);
double cap_nand_out = drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def) +
drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)*2 +
gate_C(tr_size*min_w_pmos, 0);
double cap_ptrans_out = 2 *(drain_C_(tr_size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(tr_size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)) +
gate_C(s1*(min_w_nmos + min_w_pmos), 0);
double tc = res_nor * cap_nand_out + (res_nor + res_ptrans) * cap_ptrans_out;
delay += horowitz (w1.out_rise_time, tc,
deviceType->Vth/deviceType->Vdd, deviceType->Vth/deviceType->Vdd, RISE);
//nand
power.readOp.dynamic += 0.5 *
(2*drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def) +
gate_C(tr_size*(min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd;
power.searchOp.dynamic += 0.5 *
(2*drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def) +
drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def) +
gate_C(tr_size*(min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd*init_wire_bw;
//not
power.readOp.dynamic += 0.5 *
(drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+gate_C(size*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd;
power.searchOp.dynamic += 0.5 *
(drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+gate_C(size*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd*init_wire_bw;
//nor
power.readOp.dynamic += 0.5 *
(drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+ 2*drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+gate_C(tr_size*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd;
power.searchOp.dynamic += 0.5 *
(drain_C_(size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+ 2*drain_C_(size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def)
+gate_C(tr_size*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd*init_wire_bw;
//output transistor
power.readOp.dynamic += 0.5 *
((drain_C_(tr_size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+drain_C_(tr_size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def))*2
+ gate_C(s1*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd;
power.searchOp.dynamic += 0.5 *
((drain_C_(tr_size*min_w_pmos, PCH, 1, 1, g_tp.cell_h_def)
+drain_C_(tr_size*min_w_nmos, NCH, 1, 1, g_tp.cell_h_def))*2
+ gate_C(s1*(min_w_nmos + min_w_pmos), 0)) *
deviceType->Vdd * deviceType->Vdd*init_wire_bw;
if(uca_tree) {
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*tr_size*2, min_w_pmos*tr_size*2, 1, inv)*deviceType->Vdd*wire_bw;/*inverter + output tr*/
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nand)*deviceType->Vdd*wire_bw;//nand
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nor)*deviceType->Vdd*wire_bw;//nor
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*tr_size*2, min_w_pmos*tr_size*2, 1, inv)*deviceType->Vdd*wire_bw;/*inverter + output tr*/
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nand)*deviceType->Vdd*wire_bw;//nand
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nor)*deviceType->Vdd*wire_bw;//nor
//power.readOp.gate_leakage *=;
}
else {
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*tr_size*2, min_w_pmos*tr_size*2, 1, inv)*deviceType->Vdd*wire_bw;/*inverter + output tr*/
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nand)*deviceType->Vdd*wire_bw;//nand
power.readOp.leakage += cmos_Isub_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nor)*deviceType->Vdd*wire_bw;//nor
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*tr_size*2, min_w_pmos*tr_size*2, 1, inv)*deviceType->Vdd*wire_bw;/*inverter + output tr*/
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nand)*deviceType->Vdd*wire_bw;//nand
power.readOp.gate_leakage += cmos_Ig_leakage(min_w_nmos*size*3, min_w_pmos*size*3, 2, nor)*deviceType->Vdd*wire_bw;//nor
//power.readOp.gate_leakage *=deviceType->Vdd*wire_bw;
}
}
