Our customer designs radio frequency chips such as power amplifiers, switches and low-noise amplifiers (LNA).

When a chip is received from the fab after manufacturing, there is a need to test and characterize its analog front-end. This is done by programming parameters through a digital interface and by measuring the resulting behaviour of the chip. A whole testing program can be applied, through sequential programming and measurement steps.

The configuration port used by this company used to be easily controllable with a microcontroller and a GPIO. With time our customer had progressively replaced the chip's interface with custom serial interfaces using a protocol close to SPI. To spare pins, some of these interfaces used a 3 wires serial interface (clock, data and chip select).

Customer's requirements

- the customer needed a device to allow their engineers to manually test of the chips after manufacturing;
- the solution had to be able to communicate with the RF chip with 3- wires and 4- wires SPI protocol and some other protocols on larger parallel busses;
- unlike the old GPIO interface (low speed, essentially static), the new protocols required a precise timing (up to several tenth of MHz) which could not be fulfilled with microcontrollers;
- the solution had to be programmable with Visual Basic as there is an important base of test programs available in this language within the company;
- the solution had to be compact enough to be able to use it from the designer's desk; for instance, it had to be portable and powered through USB;
- optionally, this solution had to be deliverable as an PC interface device to the customer's own customers with a demonstration kit for the RF chips.

Byte Paradigm's solution

Byte Paradigm proposed 2 solutions based on SPI Xpress device and GP series devices (GP-22050 first, then GP-24100 ).

SPI Xpress was already able to interface any standard SPI interface on 4 wires (SCLK, SS, MISO, MOSI) and could be controlled by means of C/C++ programs. Byte Paradigm extended the functionalities of SPI Xpress to allow it to interface 3-wires SPI interfaces, where the MOSI and MISO lines are merged as a single bidirectional data line. Byte Paradigm also offered guidelines to this customer to help him call the C/C++ DLL functions from Visual Basic. The 3-wires interface is new available in standard with SPI Xpress

Finally, when the customer required other custom interfaces, Byte Paradigm proposed the GP Series devices, which offer the same capabilities as the SPI Xpress and are also able to function as a general purpose Digital Pattern Generator. As a digital pattern generator, a GP device is able to stimulate any digital interface up to 16 bit wide, with arbitrary logic patterns. This mode of operation of GP series device offered the flexibility required by the customer, with GP-22050 first (max. pattern frequency: 50 MHz), and now with GP-24100 (max. pattern frequency 100 MHz).

Recommended products

- SPI Xpress for 3-wires and 4-wires serial interfaces up to 50 MHz
- GP Series devices in Digital Pattern Generator mode for stimulus generation on other custom digital interfaces (up to 100 MHz).