SaymaAFE - sinara-hw/meta GitHub Wiki

RF Front-End Mezzanines

Mezzanines providing analogue front-ends (AFEs) for the ADCs and DACs on Sayma.

Available AFEs

TestMod

Simple mezzanine designed for thermal and connectivity testing, and to serve as a template for other mezzanine designs.

To do: add image and description of functionality.

Design files are here, the schematic is here.

BaseMod

BaseMod is a base-band input/output mezzanine. Design files are here, the schematic is here.

NB: 12/2017 Allaki was renamed BaseMod.

Outputs

BaseMod provides two independent RF outputs, featuring:

  • Bandwidth: 10MHz - 4GHz (upper frequency is limited by several different components)
  • Max output power: ?dBm (limited by ?).
  • Output filters: either 3 Mini-Circuits FV1206 series filters, or a user-definable discrete 9-pole discrete-element filter using 0402 components.
  • Low phase noise amplifier: Mini-Circuits ERA-4XSM+); 14.2dBm gain at 1GHz.
  • Digitally programmable attenuator: HMC542BLP4E; 0dB to 31.dB in 0.5dB steps; controllable in real-time.
  • Fast, high-isolation RF switch: HMC349LP4C; 67dB isolation at 1GHz; controllable in with real-time control.
  • Power detector: AD8363ACPZ on switch "off" port for monitoring and power levelling.
  • Optional isolation of output grounds: to avoid ground loops, achieved by fitting capacitors and washers.

MicrowaveOffice simulations of several output filters were discussed and the models are in source.

Inputs

BaseMod provides two independent inputs, each of which can be configured (component placement) as:

  1. Direct feed to ADC via ADA4927-1 buffer for maximum bandwidth

  2. Low-noise programmable gain instrumentation amplifier (AD8253) front-end

  • Bandwidth: DC-300kHz
  • Input ranges: ±0.1V, ±1V, ±10V
  • Fully differential inputs: 100k between each input signal and ground and the circuit ground
  • Filters: Common-mode and differential mode filtering of RF interference for optimum DC precision
  • Input protection: diodes between each input and the supply rails for maximum ruggedness
  • Supports both high-speed input directly coupled into a high-speed pre-amp, and low-frequency inputs using a variable-gain instrumentation amplifier (choice by component selection). Pull details from #81
  • Instrumentation amp: gain, filters, etc.

MixMod

MixMod is an up-converting mezzanine, using an analogue IQ mixer to mix the input and output RF signals with a LO supplied by Sayma.

The LO provided by Sayma should be a 3V3 PECL square-wave.

Outputs

MixMod provides a single RF output between 2.5GHz and 3.5GHz, produced by mixing two DAC channels with a LO supplied by Sayma. Other than the IQ mixer, the output signal-chain is identical to BaseMod.

Inputs

MixMod's two inputs can either be operated in baseband or downconversion mode (selectable by component choice). In baseband mode, the inputs function identically to BaseMod's. In downconversion mode, a single SMA input feeds the RF port on an IQ mixer to produce a pair of baseband signals, which then feed the two signal chains.

General Specification

Mechanical

  • Board size
  • Mounting holes
  • SMA locations and pns
  • Connectors

Electrical

  • Suggest ADL5375 IQ modulator. Good intrinsic carrier/sideband rejection, relatively low temp coefficients, sufficient IF bandwidth, good I/Q linearity. This is the chip used in the NIST Magtrap drive system.
  • Signal levels etc