TriQuint Semiconductor, Inc. introduced the TQ5121, a 3V RF receiver IC designed specifically for Cellular band TDMA applications. Its RF performance meets the requirements of products designed to both the digital TDMA IS-136 standard and analog cellular AMPS standard. The TQ5121 is pin compatible with the previously introduced TQ9222 (dual band receiver), allowing handset manufacturers the advantage of using the same printed circuit board design for both single band cellular and dual band TDMA handsets minimizing design time, cost, and time to market.

Additionally, the TQ5121 can be used for receiving functions in products designed for the 900 MHz ISM Industrial/Scientific/Medicine (ISM) Band. The small size and excellent performance of the TQ5121 make it attractive for any TDMA or AMPS handset or ISM equipment application. The RFIC uses minimal off-chip matching components while maintaining maximum performance including high output Third Order Intercept efficiency. Small current drain, small physical size, and low cost make this part ideal for portable, battery operated applications.

The TQ5121 configuration integrates a GaAs MESFET RF LNA, a buffered local oscillator (LO) input, a GaAs MESFET mixer, and an IF output amplifier all integrated in a single, small RFIC.

ęThe high level of integration and pin compatibility with the TQ9222 makes the TQ5121 ideal for hand-held applications where multiple bands, small size, low current consumption, and high performance are necessary.ę said Cathy Arb, Product Marketing Engineer for TriQuintęs Wireless Products.

PERFORMANCE
The TQ5121 has typical conversion gain of 17.5 dB and a noise figure of 2.7dB over operating conditions and frequency. Input third order intercept point is -8.5 dBm minimum and a high-side local oscillator frequency approach is utilized enabling low IF frequency capability within the IF frequency range of 70 to 140 MHz.

Operating temperature range is -40 to +85 degrees C. This level of electrical performance is achieved with a single operating voltage of +2.8 to +3.6 volts and 10 mA of current. This voltage is normally supplied by either a single lithium-ion or three nickel metal hydride (NiMH) battery cell(s).

Most RF ports are matched to 50 ohms. The IF output port requires external components to optimize performance. However, these components allow the user flexibility in IF bandwidth and IF impedance levels with only a series/shunt capacitor combination. RF, IF, and LO port return losses are greater than 10 dB.

APPLICATIONS
The TQ5121 offers a new level of performance with features well suited for the growing number of applications for Worldwide Cellular Mobile phones (TDMA/AMPs) and the 900 MHz ISM bands.

This is a major "protection" product for the world's manufacturers of handsets. Recent Asean economic events stressed the market balance of dual vs. single band handsets could change quite dramatically -- and very quickly -- and some of the manufacturers learned the need to be rather more flexible in their production output. Obviously a circuit design that allows for dropping in either a single or dual-band receiver part would considerably increase that flexibility. The TQ5121 is really a single-frequency version of the TQ9222 and it exhibits performance numbers similar to the 900-MHz part of that part. It will be an extremely viable product for TriQuint, although I really would want a better noise figure than 2.7 dB for the majority of ISM applications; neither do I think that 10-dB return losses are much to crow about. I do, however, love the 900-MHz input match that is built in to the IC. The architecture situation in having to match the output of the IF sounds like a hassle but, in fact, it makes for a much more flexible approach as to where you have the IF, how wide it is, and even whether there are not circuit simplifications that can be made by moving the impedance.