ML5825

ADVANCED DATASHEET

SEPTEMBER 2007

EDS-106038 REV A01

9

FUNCTIONAL DESCRIPTION

The ML5825 is a monolithic, bilateral 2.4GHz to 5.8GHz frequency translator. It provides a simple and straightforward

solution for designers of 2.4GHz products who want to develop advanced products for the relatively interference-free

5.8GHz band, especially digital cordless telephones. The ML5825 can implement “dual band” solutions that use both

the 2.4GHz and 5.8GHz bands as well as “hybrid” products where one link (say, basestation transmission) is at 5.8GHz,

while the other link (basestation receive) is at 2.4GHz.

5.8GHz signals enter the RXI pin and then are fed to an LNA and bandpass filter. An image-reject downconvert mixer

translates the signal to the 2.4GHz ISM band where it is then buffered and sent off chip differentially on RXON/RXOP.

The receive signal path can be configured for either a “High Gain” mode (about 13dB) or “Low Gain” mode (-8dB). Gain

mode is selected via the RXGN digital input pin. High Gain mode is used for low-level input signals to minimize Noise

Figure while Low Gain mode optimizes input IP3 for stronger signals.

2.4GHz signals come into the ML5825 differentially on the TXIP/TXIN pins, where they are upconverted to 5.8GHz,

bandpass filtered, and then amplified and exit via TXO. The predriver/buffer output power compression point is

programmed by an external resistor that sets the preamp bias level.

A fully integrated phase locked loop (PLL) generates the fixed local oscillator (LO) at 3342.336 MHz which is used for

upconverting and downconverting the RF signals. The comparison frequency of the PLL is derived from the frequency

reference present on the FREF pin and the state of REFSEL as shown in Table 1. The PLL loop filter is external to the

ML5825 so that lock time and in-band phase noise can be optimized for the system of interest.

REFSEL

REFERENCE

DIVISION

FREF

3

18.432 MHz

4

24.576 MHz

Table 1: ML5825 Frequency References

The ML5825 contains two separate bandgap references and several low dropout (LDO) voltage regulators to insure

consistent performance over supply voltage and minimize crosstalk on chip. The device is enabled by bringing XCEN to

mode.

MODES OF OPERATION

The ML5825 has three key modes of operation. The two operational modes are RECEIVE and TRANSMIT, controlled

by TXON. XCEN is the chip enable/disable control pin, which sets the device in operational or STANDBY modes. The

relationship between the parallel control lines and the mode of operation of the IC is summarized in Table 2.

XCEN

TXON

MODE NAME

FUNCTION

0

X

STANDBY

Standby. All circuits powered down

1

0

RECEIVE

Receive Chain Active

1

1

TRANSMIT

Transmit Chain Active

Table 2: Modes of Operation