Design of LNA+Mixer for Multi-Band WCDMA

Design of LNA+Mixer for Multi-Band WCDMA

Mallya Perdoor, S.

De Vreede, L. (mentor)
Barre, P. (mentor)
Akhnoukh, A. (mentor)
Long, J. (mentor)

Electrical Engineering, Mathematics and Computer Science

Microelectronics

2009-07-13

A small, low-cost, single-chip multi-band WCDMA/GSM transceiver solution is needed to address the high growth segment of 3G enabled smart phone ICs, while still keeping compatibility with widely deployed 2G GSM networks. In this thesis, an inductor-less LNA+mixer combination for multi-band WCDMA is presented. By designing the mixer for high IIP2, the inter-stage saw filter between LNA and mixer, as is normally used in WCDMA receiver designs has been eliminated, resulting in substantial cost reduction. Although mainly intended for WCDMA, the LNA+mixer combination also meets the requirements for GSM. For the LNA design, a noise cancellation topology has been used to achieve wide-band input matching, while still providing the required low noise figure. For this configuration, tradeoffs between noise, linearity and power consumption are explored in detail. Several modifications over basic noise cancellation topology are presented, which result in a significant reduction in noise figure. A passive mixer topology with a switching core followed by transimpedance amplifier (TIA) has been used for the mixer design. To reduce the noise contribution of the TIA, a new approach, which makes use of a current buffer between the switching core and the TIA is presented. This current buffer also allows the use of higher gate lengths and widths for the switching core transistors, which is beneficial in meeting the high IIP2 required to eliminate the inter-stage saw filter. The design of the transimpedance amplifier is also explained in detail. The LNA+mixer combination presented in this thesis achieves a worst case total gain of 35.5dB and noise figure of 2.9dB across all WCDMA bands. S11 is below -15dB from 870MHz to 2.17GHz. The IIP2 at transmit frequency offset is greater than 50dBm across all WCDMA bands. Across all these bands, the worst case IIP3 at transmit frequency offset is -8.2dBm and input referred 1dB cross compression point is -20dBm. The combination of LNA and I/Q mixer consumes 25mA from 1.2V supply. The design has been carried out using IBM 65nm CMOS process technology.

multi-band
WCDMA
LNA
mixer
noise cancelation
IIP2

http://resolver.tudelft.nl/uuid:a6f32b78-8621-445d-8690-7bb56802aea3

Student theses

master thesis

(c) 2009 Mallya Perdoor, S.