QubitPulseGenerator

Multi-Channel Programmable Pulse Generator for Qubit Control

Features

• Original pulse_gen core preserved unchanged.
• multi_pulse_gen wraps up to 4 independent channels with shared clock and reset.
• Parallel register-style control interface with combinational reads and synchronous writes.
• Per-channel width, period, and enable control.
• OR-ed busy output for system-level arbitration.
• Self-checking simulation benches for the scalar core and the multi-channel wrapper.
• Formal assertion module for pulse_gen.
• Python waveform generator that emits docs/waveform.png at 600 DPI.

Quick Start

1. git clone https://github.com/a0ax/QubitPulseGenerator.git
2. cd QubitPulseGenerator/scripts
3. make sim wave

The waveform image is written to docs/waveform.png.

Modules

pulse_gen

Parameters

| Parameter | Default | Description | | — | —: | — | | WIDTH_BITS | 8 | Width register size | | PERIOD_BITS | 16 | Period register size |

Ports

| Port | Direction | Width | Description | | — | — | — | — | | clk | input | 1 | Clock | | rst_n | input | 1 | Active-low reset | | enable | input | 1 | Enables pulse generation | | width | input | WIDTH_BITS | High-time in cycles | | period | input | PERIOD_BITS | Period in cycles | | pulse | output | 1 | Generated pulse | | busy | output | 1 | High while the generator is active |

Instantiation

pulse_gen #(
	.WIDTH_BITS(8),
	.PERIOD_BITS(16)
) u_pulse_gen (
	.clk(clk),
	.rst_n(rst_n),
	.enable(enable),
	.width(width),
	.period(period),
	.pulse(pulse),
	.busy(busy)
);

multi_pulse_gen

Parameters

| Parameter | Default | Description | | — | —: | — | | WIDTH_BITS | 8 | Shared width register size | | PERIOD_BITS | 16 | Shared period register size | | DATA_BITS | max(WIDTH_BITS, PERIOD_BITS) | Parallel bus width | | NUM_CHANNELS | 4 | Number of instantiated channels |

Ports

| Port | Direction | Width | Description | | — | — | — | — | | clk | input | 1 | Shared clock | | rst_n | input | 1 | Active-low reset | | channel_sel | input | 2 | Channel selector | | wr_en | input | 1 | Write strobe | | addr | input | 2 | Register address: 0=width, 1=period, 2=control | | wr_data | input | DATA_BITS | Write data | | rd_data | output | DATA_BITS | Combinational read data | | pulse_out | output | NUM_CHANNELS | Per-channel pulses | | busy | output | 1 | OR of all channel busy signals |

Instantiation

multi_pulse_gen #(
	.WIDTH_BITS(8),
	.PERIOD_BITS(16),
	.NUM_CHANNELS(4)
) u_multi_pulse_gen (
	.clk(clk),
	.rst_n(rst_n),
	.channel_sel(channel_sel),
	.wr_en(wr_en),
	.addr(addr),
	.wr_data(wr_data),
	.rd_data(rd_data),
	.pulse_out(pulse_out),
	.busy(busy)
);

Simulation

Existing script

The legacy simulator script remains available for the scalar core:

cd scripts
vsim -c -do sim.do

or

cd scripts
vivado -mode batch -source sim.do

Scalar testbench

sim/tb_pulse_gen.sv is a bounded, self-checking testbench with edge cases and 50 randomized (width, period) pairs.

Multi-channel testbench

sim/tb_multi_pulse_gen.sv programs all four channels, checks register reads, verifies independent pulse streams, and exercises the OR-ed busy output.

Icarus Verilog flow

iverilog -g2012 -o build/tb_pulse_gen.vvp rtl/pulse_gen.sv sim/tb_pulse_gen.sv
vvp build/tb_pulse_gen.vvp

iverilog -g2012 -o build/tb_multi_pulse_gen.vvp rtl/pulse_gen.sv rtl/multi_pulse_gen.sv sim/tb_multi_pulse_gen.sv
vvp build/tb_multi_pulse_gen.vvp

Synthesis

Vivado can target either the scalar core or the multi-channel wrapper.

create_project pulse_gen ./build -part xc7a100tcsg324-1
add_files ../rtl/pulse_gen.sv
add_files ../rtl/multi_pulse_gen.sv
add_files -fileset constrs_1 ../constraints/pulse_gen.xdc
launch_runs impl_1 -to_step write_bitstream
wait_on_run impl_1

Use multi_pulse_gen as the top level when you want the multi-channel subsystem.

Testing

• sim/tb_pulse_gen.sv checks reset, disabled behavior, width=0, period=0, width=period, width>period, enable toggling, reset during operation, and 50 randomized cases.
• sim/tb_multi_pulse_gen.sv checks register programming, readback, independent channel output timing, and busy aggregation.
• sim/pulse_gen_assert.sv can be bound to pulse_gen for formal or assertion-based simulation.

Waveform

The generated timing diagram is shown below and is created by scripts/generate_waveform.py.

Timing Closure

report_timing_summary -delay_type max -report_unconstrained -max_paths 10 -file timing_summary.rpt

Verify in timing_summary.rpt that WNS >= 0 and Fmax exceeds 100 MHz.

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