TD-SCDMA RD V2.1 Design Meets Rx-Blocking Mask and Sensitivity Requirements - Application Note - Maxim

This application note introduces Maxim's 2nd-generation TD-SCDMA radio frequency transceiver chipset with its V2.1 reference design. It also discusses some of the key system issues, such as sensitivity and blocker tests, that warrant careful consideration in order to create an optimum TDSCDMA RF design. Maxim TD-SCDMA RF Transceiver Chipset Maxim's TD-SCDMA mobile-phone RF chipset consists of the MAX2507 (Tx) and the MAX2392 (Rx). Both RF ICs are fabricated using Maxim's in-house, high-frequency process technology. The MAX2507 is a fully-integrated transmitter chip that includes circuits from analog I/Q input to power-amplifier output. Its main functional blocks include an I/Q quadrature modulator, an upconverter, a variable-gain amplifier (VGA), an RF voltage-controlled oscillator (VCO) and phase-locked loop (PLL), IF local oscillator generation, and an RF power amplifier (PA). This device is packaged in a 7mm x 7mm land grid array (LGA). The companion zero-IF receiver, the MAX2392, includes circuits from a low-noise amplifier (LNA) to analog I/Q output. Its main functional blocks include an LNA, an RF I/Q demodulator, RF VCO and PLL circuitry, baseband channel-select filters, DC-offset correction circuitry, and automatic gain control (AGC) baseband amplifiers. The MAX2392 is housed in a 5mm x 5mm QFN package. A complete reference design that facilitates the OEM radio RF board design shows an effective overall PCB size of 6.6cm2. The functional block diagram of the reference design is shown in Figure 1 and a photograph of the reference board in Figure 2. Rx Requirements in TD-SCDMA Standard The main Rx requirements of the TD-SCDMA standard are shown in Table 1. The minimum sensitivity that needs to be met is -108dBm, while the blocking spec is a canyon shape with frequency offset.