FUNCTIONAL DESCRIPTION
The ML5824 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 ML5824 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 14dB) or “Low Gain” mode (-4dB). 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 ML5824 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 3343.68MHz 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
ML5824 so that lock time and in-band phase noise can be optimized for the system of interest.
REFSEL REFERENCE
DIVISION
FREF
VIL
VIH
3
4
10.368MHz
13.824MHz
Table 1: ML5824 Frequency References
The ML5824 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
VIH and is placed in transmit mode by setting TXON to VIH. With XCEN at VIL the ML5824 enters a low power standby
mode.
MODES OF OPERATION
The ML5824 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
1
1
X
0
1
STANDBY
RECEIVE
TRANSMIT
Standby. All circuits powered down
Receive Chain Active
Transmit Chain Active
Table 2: Modes of Operation
STANDBY MODE
In STANDBY mode, the ML5824 transverter is powered down. When exiting STANDBY mode, the transmitter is
disabled for 200µs. However, the receive path is not similarly locked out and so will receive invalid data for up to 200µs.
Therefore, the system should wait 200µs after exiting STANDBY mode before actively processing signals to allow the
PLL to lock. A timing diagram for the ML5824 is shown in Figure 2.
DS5824-F-01
FINAL DATASHEET
AUGUST 2004
9
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
