S5k - 16 Channel AWG
Description
The S5k is a multi-channel arbitrary waveform generator. It offers up to 16 independent output channels or up to 8 combined channels with summed outputs. The S5k can be run with either arbitrary (user-given) waveforms or with a selection of built-in waveforms. The S5k has 4 modes of output:
Sawtooth: These are pre-set common waveform types. The waveform can be configured as either 'Positive Sawtooth' (gradual increase, sharp drop), 'Negative Sawtooth' (sharp rise, gradual decrease), 'Triangle Wave' (gradual increase and decrease). The repetition settings allow for back-to-back repetition, continous periodic repetition or numbered periodic repetition. Note that if you use only the Sawtooth mode, you may also use the Sawtooth-dedicated D5c module.
Arbitrary (AWG): This mode produces is an arbitrary waveform. The waveform is fully defined by the user in the form of a vector specifying the levels. The repetition settings allow for back-to-back repetition, continous periodic repetition or numbered periodic repetition.
DC: This mode produces a DC level in the range from 0 to the max output current set for the channel. This is available only as a continuous waveform.
Noise (Random): This mode produces pseudorandom noise on the channel output. It is available only as a continuous waveform.
Some S5k programming examples are available on the links below. These are a good open-source reference, but have not been fully verified:
- S5k_module
- S5k_Low_Level
- More info on programing the S5k is on the S5k software page
The S5k provides great flexibility in clocking frequency. The baseline clock serving the waveform generation can be either external clock provided by the user or a built-in 200MHz clock source. This baseline frequency can be used as-is or divided down by any even factor up to 510. Note that each group of 4 output channels shares the same selected frequency.
Note that as of 2023 the S5k has two versions are:
Version 1.0 (with initial HW version): module addressing is done via jumper-given. The trigger time counter has a 14-bit limit.
Version 1.1 (with later HW version): module addressing is slot-based within the SPI rack. The trigger time counter has a 16-bit limit.
The module version is written on a sticker on the module side / front.
Working with external Clocks
The S5k can use either of two clock sources - an intrenal 200MHz signal or an external clock provided through the 'RF Reference' connector at the back of the SPI rack. The most common frequency chosen is 10MHz but the SPI rack input can support frequencies up to 200MHz.
The external signal must meet several requirements. It is up to the user to ensure these are met:
Frequency: 1 to 200 MHz.
Slew rate : min. 0.5V/ns (between 20%-80% levels).
Duty Cycle: 30% to 70%.
Power: -13 to 5 dBm (AC coupled inputs).
Custom Options and Modifications
The S5k output path can be optimized for various parameters such as large swing, fast transitions, or DC stability. These all use different hardware so the choice is best made when ordering an S5k. Another choice is for the number of output channels, typically 8 or 16.
Another custom build of the S5k is a summing unit where internal AWG signals are combined with signals from an external source. Typically these would be DC/low-freq signals from a D5a module, as it can provide more precise DC levels (18-bit vs 12-bit precision). The signal available at the S5k output connector has contributions from both sources, each of them scaled and shifted according to the proportions of the different impedances in the full circuit.
Caution: In this construction the intended mode of operation is with both sources present and active in the circuit. When the external DC source is unplugged or not yet connected, the resistor divider structure is absent - the AWG signal is not scaled down, which delivers the full amplitude to the S5k output. This could potentially harm a sample.
Specifications
| Parameter | Value | Units | Conditions |
|---|---|---|---|
| Number of channels | 16 | Independent channels | |
| Number of channels | 8 | Summed outputs | |
| Output swing | 5.8 | V | To a 50Ω load. A higher-impedance load will show larger swing. |
| Resolution | 12 | bit | |
| 1.4 | mV | On a 5.8V swing unit (default build) to a 50Ω load. | |
| Waveform memory size | up to 4096 | kSamples | Shared per 4 consecutive output channels |
| Static Characteristics | |||
| Maximum sample rate | 250 | MSps | |
| Rise time | 200 | ns | Measured 10%-90% |