Peter Bode

Baseband and audio mixed-signal front-end IC for GSM/EDGE applications

A complete mixed-signal front-end CMOS chip is presented, supporting GSM/EDGE as well as enhanced audio applications. The chosen solution for the transmit section is based on Laurents approximation of the nonlinear GMSK modulator. This enables burst shaping in the I/Q domain thereby solving the problem of power ramping. Also, up to GPRS class 12 is supported. The receive section on the other hand consists of a low power dual mode continuous-time /spl Sigma//spl Delta/ ADC for I and Q, supporting ZIF and LIF modes of operation and achieving typically 12.5 bit of resolution under production conditions. An on-chip PLL, which supplies all blocks with various clock frequencies, additionally supports clock jitter suppression. The audio section comprises a codec supporting standard formats such as IIS and PCM. It features mono/stereo signaling from various sources in 16bit quality as well as high-drive buffers for 4 /spl Omega/ single-ended loads (capacitively coupled). The whole chip is powered from a 1.5/2.65 V supply voltage and consumes 22 mW in paging mode.

Combined GMSK and 8PSK modulator for GSM and EDGE

An efficient digital GMSK/8PSK I/Q signal modulator for GSM/EDGE is presented. The solution is based on Laurents approximation of the non-linear GMSK modulator by a bank of linear, pre-encoded modulators, thus enabling burst shaping in the I/Q domain and therefore solving the problem of power ramping. The solution is compatible to all major transmitter architectures offering an I/Q interface.

Improved method for measuring frequency ratios in GSM mobile phones

The principle of operation of the ubiquitous low-cost digital circuits for frequency measurement appears to have remained unchanged for decades. In applications with very high accuracy requirements, such as in GSM mobile phones, these conventional solutions can lead to excessive measurement periods with detrimental effect on the stand-by time. In this paper, we present a novel frequency measurement technique which is based on regression algorithms. Experiments with a hardware implementation prove that the crucial product of measurement error and measurement period can be reduced by orders of magnitude compared to conventional solutions while the slight extension of the digital circuitry is virtually for free.

Correction to “Baseband and Audio Mixed-Signal Front-End IC for GSM/EDGE Applications” [Jun 06 1364-1379]

In the above titled paper (ibid., vol. 41, no. 6, pp. 1364-1379, Jun. 06), equations (6) and (7) appeared incorrectly. They are presented correctly here.