CMX972 Datasheet, PDF (4/41 Pages) CML Microcircuits – Small 32-lead VQFN Package

Quadrature Demodulator with IF PLL/VCO
CMX972
7.2 Demodulator Intermodulation and Output Drive Capability ........................... 29
7.3 Variation with Temperature............................................................................ 29
7.4 Effect of Gain Control on Receiver Performance .......................................... 30
7.5 Measurement of CMX972 Demodulator Intermodulation Performance ........ 32
7.6 Operation with large input signals .................................................................. 33
7.7 VCO Phase Noise.......................................................................................... 34
8
Performance Specification ................................................................................ 35
8.1 Electrical Performance................................................................................... 35
8.1.1 Absolute Maximum Ratings .................................................................... 35
8.1.2 Operating Limits ...................................................................................... 35
8.1.3 Operating Characteristics........................................................................ 36
8.2 Packaging ...................................................................................................... 41
Section
Page
Table 1 Pin List................................................................................................................... 7
Table 2 Power Supply Component Values......................................................................... 8
Table 3 Quadrature Demodulator Input Components ........................................................ 9
Table 4 Internal VCO Amplifier Tank Circuit for 180MHz Operation................................ 11
Table 5 3^rd Order Loop Filter Circuit for 180MHz Operation ............................................ 11
Table 6 Rx I/Q Differential to Single-ended Amplifier Components ................................. 12
Table 7 Rx Low IF (455kHz) Components ....................................................................... 13
Table 8 Typical Phase Balance, LO/2 Mode .................................................................... 15
Table 9 Recommended FREQ bit Settings in the Rx Mode Register .............................. 15
Table 10 Effect of FREQ bits ($1D, b3-b0) on I/Q Phase Balance at 250MHz................ 16
Table 11 Effect of FREQ bits ($1D, b3-b0) on I/Q Phase Balance at 300MHz with Temperature
.......................................................................................................................................... 16
Table 12 DC Offset Correction Adjustments .................................................................... 16
Table 13 LO Connections................................................................................................. 17
Table 14 PLL Control ....................................................................................................... 19
Table 15 Quadrature Demodulator Input Impedances and Parallel Equivalent Circuit .... 28
Table 16 Typical Noise Figure and Gain of IF Amp, VGA and I/Q Mixer ......................... 29
Table 17 Typical Third Order Intercept Performance of demodulator at 45MHz (straight-in case)
.......................................................................................................................................... 29
Table 18 Effect of VCONR bits, f_vco = 180 MHz, divide-by-2........................................... 34
Section
Page
Figure 1 Block Diagram ...................................................................................................... 6
Figure 2 Power Supply Connections and Decoupling ........................................................ 8
Figure 3 IF Input Match Circuit ........................................................................................... 9
Figure 4 RXLO Input Configuration .................................................................................... 9
Figure 5 Example External Components – VCO External Tank Circuit ........................... 10
Figure 6 Example External Components – PLL Loop Filter ............................................. 11
Figure 7 Example External Components – Receive I/Q Output....................................... 12
Figure 8 Example External Components – Receive Low IF Output................................. 13
Figure 9 Demodulator Gain Control ................................................................................. 14
Figure 10 Frequency Response, showing effect of COR bit ($1C, b6) and FREQ bits($1D, b3-b0)
.......................................................................................................................................... 15
Figure 11 Simplified Schematic DC Offset Correction Circuit .......................................... 16
Figure 12 PLL Architecture............................................................................................... 18
Figure 13 C-BUS Transactions ........................................................................................ 21
Figure 14 Quadrature Demodulator Input Impedance (10MHz to 300MHz) .................... 28
Figure 15 Demodulator Gain Variation With Temperature............................................... 30
Figure 16 Variation in Gain with Temperature (COR = ‘0’ $1D = 0x00) .......................... 30
Figure 17 Variation in CMX972 Demodulator Noise Figure with VGA/VGB Control ........ 31
 2015 CML Microsystems Plc
4
D/972/2