ML2724 View Datasheet(PDF) - Micro Linear Corporation
Part Name
Description
MFG CO.
'ML2724' PDF : 26 Pages View PDF
ML2724
RVVCO
33nF
150Ω
QPO
220nF
VTUNE
Example 13kHz Loop Filter
MODES OF OPERATION
There are three key modes of operation:
STANDBY:
All circuits powered down, except the control interface (Static CMOS)
RECEIVE:
Receiver circuits active
TRANSMIT:
Modulated RF output from IC
The two operational modes are RECEIVE and TRANSMIT, controlled by RXON. XCEN is the chip enable/disable
control pin, which sets the part in operational or STANDBY modes. The relationship between the parallel control lines
and the mode of operation of the IC is given in Table 1.
XCEN RXON MODE
FUNCTION
0
X
STANDBY Control interfaces active, all other circuits powered down
1
1
RECEIVE Receiver time slot
1
0
TRANSMIT Transmit time slot
Table 1: Modes of Operation
MODE CONTROL
The ML2724 is intended for use in TDD and TDMA radios in battery-powered equipment. To minimize power
consumption it is designed to switch rapidly from a low power mode (STANDBY) to an active mode. The ML2724 can
also make a quick transition from receive to transmit for TDD operation. Prior to transmitting or receiving, time should
be allowed for the PLL to lock and for the filters to align. When the ML2724 is operated in single-carrier TDD mode, the
LO is automatically shifted by the second (low) IF frequency when the device is switched between RECEIVE and
TRANSMIT modes.
ML2724 carrier frequency can be changed (hopped) at any time, but is usually changed between transmissions. Carrier
frequency (channel) is modified in the ML2724 by writing a corresponding new value to the PLL frequency register
(Register 1)
RECEIVE
The ML2724 uses a double-conversion super-heterodyne receiver with a nominal second IF of 1.024MHz. The signal
flow in RECEIVE mode is from the RF input, through an RF down-conversion mixer and integrated IF filter, image reject
quadrature mixer, integrated Low IF filter, hard limiter, frequency to voltage converter, and data filter to the AOUT pin
and data slicer where the digital NRZ data is available at the DOUT pin. A 20dB step AGC extends the dynamic range
of the receiver. The ML2724 receive chain is a Low IF receiver using advanced integrated radio techniques to eliminate
external IF filters and minimize external RF filter requirements. The precision filtering and demodulation circuits give
improved performance over conventional radio designs using external filters while providing integration comparable to
advanced direct conversion radio designs.
DS2724-F-03
FINAL DATASHEET
DECEMBER 2005 13
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