CDMA IF VGAs and I/Q Demodulators

with VCO and Synthesizer

8

_______________________________________________________________________________________

_______________Detailed Description

MAX2310

The MAX2310 is intended for dual-band (PCS and cel-

lular) and dual-mode code division multiple access

(CDMA) and FM applications (Figure 1). The device

includes an IF variable-gain amplifier, quadrature

demodulator, dual VCOs, and dual-frequency synthe-

sizers (Figure 7). Dual VCOs are provided for applica-

tions using different IF frequencies for each mode or

band of operation. The analog FM output signal can be

configured for conversion to the I channel, or it may be

converted in quadrature to both the I and Q channels.

The MAX2310’s operation modes are described in

Table 1. These modes are set by programming the con-

trol register and setting logic levels on control pins. If

MODE is left floating, the internal register controls the

operation. If driven high or low, mode will override cer-

tain register bits, as shown in Table 1.

MAX2310

BYP

BYP

FM-

FM+

CDMA+

CDMA

FM

3-WIRE

DAC

0.1

μF

0.01

μF

0.033

μF

47pF

5pF

18pF

3.3nF

10k

Ω

10k

Ω

10k

Ω

18pF

47pF

68nH

0.01

μF

680

Ω

CDMA-

LOCK

VGC

DATA

CLK

QOUT+

QOUT-

EN

TANKH-

IOUT-

IOUT+

REF

GND

MODE

TANKH+

TANKL-

GND

CPOUT

BYP

SHDN

TANKL+

0.01

μF

47pF

10k

Ω

47k

Ω

Q

I

10k

Ω

1.5pF

12pF

10k

Ω

10k

Ω

12pF

18nH

Figure 1. MAX2310 Typical Operating Circuit