R2000 datasheet(17/75 Pages) ETC

17 / 75 page

Indy® R2000 Electrical, Mechanical, & Thermal Specification

5.1.2 Local Oscillator Input

You may source the receiver local oscillator internally or externally as shown in Figure 4-1. If you do not use an

external receiver local oscillator, the DC blocking capacitors, inductor, and balun are not required.

For proper self-jammer cancellation, the local oscillator input power level must exceed the maximum self-jammer

level that requires cancellation. For more detail see section 5.3.

5.1.3 PLL Loop Filter

Figure 4-2 illustrates the recommended component values for the PLL loop filter.

Figure 4-2: PLL Loop Filter

5.1.4 Receive RF Interface

The Indy R2000 reader chip has differential RF and local oscillator ports to alleviate interference on the package

bond-wires coming from the digital section of the chip.

The Indy R2000 receiver mixer also supports a high gain and a low gain mode with differing compression points. In

order to switch between these modes, it is necessary to both correctly program the ANA_CTRL1 register as well as

bias the output of the mixer to +3.3 V through 400 ohm resistors. You may switch these bias resistors in for low gain

mode and out for high gain mode. Ensure that when switched out, the bias resistors do not create an unintended

current summing node.

5.1.5 Self-Jammer Cancellation Block

The idea behind self-jammer cancellation is to tap a signal from somewhere along the transmit path and use it as a

reference for suppressing the corresponding part of the received signal in the RF low noise amplifier. By doing so,

both the self-jammer carrier and transmit amplitude and phase noise are simultaneously suppressed. By tapping the

reference transmit signal after the external power amplifier, all transmit noise sources may be managed. As shown in

the block diagram in Figure 4-3, the reference signal is shared with the receive mixer local oscillator input.

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