ReferenceProc.v

This module adds the phase of a reference signal to a setpoint signal. The reference signal is averaged over many samples prior to the operation. When the reference accumulation is done, the Cordic rotation is initiated.

Data outputs are initially all zero. The go input initiates an accumulation cycle, after which the a Cordic rotation is initiated. Cordic rotations are subsequently automatically retriggered, unless the Testbench symbol is defined by a Verilog directive.

Ports | Parameters | Notes | Example

Ports

clk	input	The clock input.
reset	input	Reset input, which clears the accumulator and resets the module's state to the idle state.
quad	input	A two-bit quadrant fiducial.
go	input	Initiates an accumulation cycle. It may be a multi-bit vector whose width is the `gb` parameter.
in	input	The data input (setpoint) port of `w1` bits width. The phase of the reference input is added to this signal.
inMag	output	The magnitude of the `in` input scaled by 1/0.607253. It has the same bit width as `in`.
ref	input	The reference input whose phase is added to the `in` input.
refavg	output	The reference input averaged output by the internal accumulator. Its width is the same as the `in` input.
Iout	output	The in-phase (I) output.
Qout	output	The quadra-phase (Q) output.
IoutN	output	The twos-complement negative of the in-phase (I) output, synchronous with `Iout`.
QoutN	output	The twos-complement negative of the quadra-phase (Q) output, synchronous with `Qout`.
out	output	The I/Q output with the ++--... modulation for f_s/4 upconversion.
busy	output	This output indicates that a Cordic cycle is in progress.
done	output	A pulse that indicates that a Cordic cycle has completed and data are valid.

Parameters

The figure below illustrates the usage of the bit-width parameters.

w1	16	The bit width of the `in` input port.
w2	16	The bit width of the `ref` input port.
w3	16	The bit width of the five output-data ports.
ofl	10	The number of accumulator overflow bits. The number of accumulation clocks is tied to this parameter: cycles = 2^ofl.
apb	5	The number of accumulator precision bits. These bits on the lsb end of the accumulator participate in the addition of samples, but are discarded at the end of the cycle. This is done to preserve precision of the output.
gb	1	The number of bits in the `go` vector, which may be a multi-level trigger.
direction	1'b1	Whether the module adds the reference phase (1'b1) or subtracts (1'b0) to the set point.

Notes

The signal intensities of both the reference and setpoint inputs should both not be small, or else the output will be inaccurate.
The Cordic module CoRotator.v scales the setpoint output signal intensity by 1/0.607253. This factor must be taken into account to avoid overflow.

Example instantiation:

localparam		wid = 16;
wire		[wid-1:0]	Iout, Qout, out;
wire				g, busy, done;
ReferenceProc
    #(.w1(wid), .w2(wid), .w3(wid), .ofl(8), .apb(4))	
    rpinstance (
        .clk(clk),		.reset(reset),
        .go(g),			.quad(quad),
        .in(data),		.ref(d1),
        .Iout(Iout),		.Qout(Qout),		.out(out),
        .busy(busy),		.done(done)
    );