AMIS-52150
Low-Power Transceiver with Clock and Data Recovery
Data Sheet
8.3 LPFILT, Loop Filter Pin
The LPFILT pin connects the AMIS-52150 internal phase lock loop (PLL) frequency synthesizer to an external loop filter (Fig. 5). An
external loop filter allows the system designer to optimize the operation of the AMIS-52150 in order to meet the requirements for a
specific end application. For further details, refer to the application note titled “Extending to Frequencies Outside of the 403MHz
Target”.
Figure 5: Typical Loop Filter
8.4 RSSI/BG, Analog Output Pin
The RSSI/BG pin is used to output either the signal from the RSSI circuits, or to output the voltage from the bandgap voltage reference
or a bypass capacitor node, respectively. The RSSI output is a true analog representation of the received signal level. The pin can also
be programmed to output the voltage of the bandgap voltage reference. When using the AMIS-52150 in the clock and data recovery
mode, a capacitor needs to be connected from the RSSI/BG pin to ground. A typical value for this capacitor is 2.2nF. Additional
information on the CDR function can be found later in this document. Table 12 presents the registers that control the function of the
RSSI/BG pin.
Table 12: RSSVBG Pin Control Registers
RSSI Pin Definition Control Registers
Register
Name
Bits
(HEX)
0x0e
Bandgap on RSSI
3
0x1e
RSSI Ext Amp
4
States
0
1
0
1
Comments
Normal operation
BG output on RSSI*
Tri-stated
RSSI signal
*Note that device needs to be in RX, TX or crystal-on mode for bandgap voltage to be present on pin.
8.5 CREF, Current Reference Bias Pin
A resistor must be connected to the CREF pin to provide a current bias to the internal bandgap voltage reference circuit. It is critical
that this resistor value is 33.2KΩ (with one percent or better tolerance) to achieve proper operation of the bandgap voltage reference.
AMI Semiconductor
– Apr. 07 – M-20535-006
www.amis.com
8
AMI [ AMI SEMICONDUCTOR ]
