Radio is a device that wirelessly transmit or receive signals in the radio frequency (RF) part of the electromagnetic spectrum to facilitate the transfer of information. The front-end of a radio is comprised of transmitter and receiver. The block diagram of a simple transceiver is shown in Figure.1. Eg. Cellular/mobile radio communications, WLAN, etc.,
With ever increasing demand to reduce the cost and size of communication equipment, the off-chip components are moving to on-chip. Most of the architectures used in present day radios are more than half-a-century old. With proliferation of integrated circuit(IC) technology, various modifications to the existing architectures are being proposed with varieties of trade-offs. But the underlying principle of circuit design is the same. With technology scaling/advances, some of the parameters are favoring RF circuit design and some others not in ICs. The problem lies in those parameters that are negligible in the traditional small-signal analog design, becomes considerable with at radio frequencies. So it is essential to understand the circuit techniques and design considerations of various building blocks in RFIC design. RF circuit and system designs need their own design methodology. Along with circuit design techniques and understanding of various building blocks, the big picture of overall design always help the designer to foresee the issues associated with the integration of transceiver components on to a chip.
Some RF building blocks, which are of high interest in integrated transceiver design, are:
- Low Noise Amplifiers
- Clock generators
- Power Amplifiers
- Onchip passive components (Inductor, Capacitor and transformer)
Since the designs are parasitic sensitive, CAD tools are extensively used for validating the design and functionality.
- Circuit(SPICE) simulators : Agilent’s Advance Design System (ADS), Cadence ADE
- EM Tools: Sonnet, Momentum, HFSS