forked from M-Labs/artiq
add some docs
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@ -1279,6 +1279,110 @@ class PhaserOscillator:
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class Miqro:
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"""
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Miqro pulse generator.
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Notes
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-----
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* The `_mu` suffix in method names refers to parameters and data in "machine units",
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i.e. integers. Conversion methods and wrappers to convert from SI units (Hz frequency,
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full scale amplitude, turns phase, seconds time) are provided.
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* The annotation that some operation is "expensive" does not mean it is impossible, just
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that it may take a significant amount of time and resources to execute such that
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it may be impractical when used often or during fast pulse sequences.
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They are intended for use in calibration and initialization.
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Functionality
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-------------
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A Miqro instance represents one RF output.
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The output is generated by with the following data flow:
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### Oscillators
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* There are n_osc = 16 oscillators with oscillator IDs 0..n_osc-1.
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* Each oscillator outputs one tone at any given time
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I/Q (quadrature, a.k.a. complex) 2x16 bit signed data
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at tau = 4 ns sample intervals, 250 MS/s, Nyquist 125 MHz, bandwidth 200 MHz
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(from f = -100..+100 MHz, taking into account the interpolation anti-aliasing
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filters in subsequent interpolators),
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32 bit frequency (f) resolution (~ 1/16 Hz),
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16 bit unsigned amplitude (a) resolution
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16 bit phase (p) resolution
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* The output phase p' of each oscillator at time t (boot/reset/initialization of the
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device at t=0) is then p' = f*t + p (mod 1 turn) where f and p are the
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(currently active) profile frequency and phase.
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The terms "phase coherent" and "phase tracking" are defined to refer to this
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choice of oscillator output phase p'.
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Note that the phase p is not accumulated (on top of previous
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phases, previous profiles, or oscillator history). It is "absolute" in the
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sense that frequency f and phase p fully determine oscillator
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output phase p' at time t. This is unlike typical DDS behavior.
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* Frequency, phase and amplitude of each oscillator are configurable by selecting one of
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n_profile = 32 profiles 0..n_profile-1. This selection is fast and can be done for
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each pulse.
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* Note: one profile per oscillator (usually profile index 0) should be reserved
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for the NOP (no operation, identity) profile, usually with zero
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amplitude.
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* Data for each profile for each oscillator can be configured
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individually. Storing profile data should be considered "expensive".
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### Summation
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* The oscillator outputs are added together (wrapping addition).
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* The user must ensure that the sum of oscillators outputs does
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not exceed the (16 bit signed) data range. In general that means that the sum of the
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amplitudes must not exceed the range.
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### Shaper
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* The summed output stream is then multiplied with a the complex-valued output of a
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triggerable shaper.
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* Triggering the shaper corresponds to passing a pulse from all
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oscillators to the RF output.
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* Any previously staged profiles and phase offsets become active simultaneously
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(on the same output sample) when triggering the shaper.
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* The shaper reads (replays) window samples from a memory of size n_window = 1 << 10 starting
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and stopping at memory locations specified.
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* Each window memory segment starts with a header determining segment
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length and interpolation parameters.
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* The window samples are interpolated by a factor (rate change) r where log2(r) = 0..n_cic=12
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selectable when triggering.
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* The interpolation order is constant, linear, quadratic, or cubic. This
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corresponds to interpolation modes from rectangular window (1st order CIC)
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or zero order hold) and to Parzen window (4th order CIC, cubic spline),
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selectable when triggering.
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* This results in support for pulse lengths of between tau and a bit more than
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(1 << 12 + 10) tau ~ 17 ms.
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* Windows can be configured to be head-less and/or tail-less, meaning, they
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do not feed zero-amplitude samples into the shaper before and after
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each window. This is used to implement pulses with arbitrary length or
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CW output.
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* The window memory can be segmented by choosing different start indices
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to support different windows selectable when triggering.
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### DAC
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* This section of the data flow is analogous to the `base` Phaser mode.
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* The DAC receives the 250 MS/s I/Q data stream and interpolates it to 1 GS/s I/Q
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(with a bandwidth 200 MHz).
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* It then applies a (expensive to change) frequency offset of
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f1 = -400 MHz..400 MHz.
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* Then the DAC converts the data stream to 2 analog outputs I and Q.
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* The signals go through two anti-aliasing filters with 340 MHz 3dB bandwidth.
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### IQ Mixer and PLL (Upconverter variant)
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* The analog I and Q signals after the filter are upconverted in a single-sideband IQ
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mixer with a f2 = 0.3 GHz..4.8 GHz LO (the "carrier").
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* The output goes through a digitally switchable attenuator (0..31.5 dB attenuation) and
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is available at an SMA output with a typical max signal level of 0 to -10 dBm (TBC).
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### Overall properties
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* The resulting phase of that signal is
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(f + f1 + f2)*t + p + s(t - t0) + p1 + p2 (mod 1 turn)
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where p1 and p2 are constant but arbitrary and undetermined phase offsets of the
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two (common) upconversion stages, s(t - t0) is the phase of the interpolated
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shaper output, and t0 is the trigger time (fiducial of the shaper).
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Unsurprisingly the frequency is the derivative of the phase.
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* The minimum time to change profiles and phase offsets is ~128 ns (estimate, TBC).
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This is the minimum practical pulse interval.
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"""
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def __init__(self, channel):
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self.channel = channel
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self.base_addr = (self.channel.phaser.channel_base + 1 +
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@ -1314,7 +1418,7 @@ class Miqro:
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(asf & 0xffff) | (pow << 16))
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@kernel
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def set_profile(oscillator, profile, frequency, amplitude, phase=0.):
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def set_profile(self, oscillator, profile, frequency, amplitude, phase=0.):
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# frequency is interpreted in the Nyquist sense, i.e. aliased
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ftw = int32(round(frequency*((1 << 30)/(62.5*MHz))))
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asf = int32(round(amplitude*0xffff))
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