ADMV1013ACCZ-R7 datasheet(25/39 Pages) AD

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Data Sheet

ADMV1013

Rev. A | Page 25 of 39

THEORY OF OPERATION

The ADMV1013 is a wideband microwave upconverter optimized

for microwave radio designs operating in the 24 GHz to 44 GHz

RF frequency range. See Figure 1 for a functional block diagram

of the device. The ADMV1013 digital settings are controlled via the

SPI. The ADMV1013 has two modes of operation:

•

Baseband quadrature modulation (I/Q mode)

•

Single-sideband upconversion (IF mode)

START-UP SEQUENCE

To use the voltage control RF VVA1 and RF VVA2, the

VCC_VVA (1.8 V) supply must be on. The VCTRL1 pin and

VCTRL2 pin control the gain of the RF VVA1 and the RF

VVA2. Similarly, to use the SPI control, it is necessary to first

turn on DVDD and then perform a hard reset by toggling the

RST pin to logic low and then to logic high.

The ADMV1013 SPI settings require the default settings to be

changed during startup for optimum performance.

Set Register 0x0A to 0xE700 after each power-up or reset.

BASEBAND QUADRATURE MODULATION

(I/Q MODE)

In I/Q mode, the input impedance of the baseband pins (I_P,

I_N, Q_P, and Q_N) are 100 Ω differential. These inputs can be

loaded with a dc-coupled 100 Ω differential load. I_P and I_N

are the differential baseband I inputs, and Q_P and Q_N are the

differential baseband Q inputs. These inputs can operate from a

VCM of 0 V to 2.6 V. The baseband I/Q ports can operate from

dc to 6.0 GHz at each I and Q channel.

To set the ADMV1013 in I/Q mode, set MIXER_IF_EN bit

(Register 0x03, Bit 7) to 0.

When changing the external VCM, the internal mixer gate

voltage also must be changed. To make this change, set the

MIXER_VGATE bits (Register 0x05, Bits[6:0]). The MIXER_

VGATE value follows the VCM such as, that for a 0 V to 1.8 V

VCM, MIXER_VGATE = 23.89 VCM + 81, and for a >1.8 V to

2.6 V VCM, MIXER_VGATE = 23.75 VCM + 1.25.

SINGLE-SIDEBAND UPCONVERSION (IF MODE)

The ADMV1013 features the ability to upconvert a real IF input

anywhere from 0.8 GHz to 6.0 GHz while suppressing the

unwanted sideband by typically better than 26 dBc. The IF

inputs are quadrature to each other, 50 Ω single ended, and are

internally dc-coupled. IF_I and IF_Q are the quadrature IF inputs.

An external 90° hybrid is required to select the appropriate

sideband. To configure the ADMV1013 in IF mode, set the

MIXER_IF_EN bit (Register 0x03, Bit 7) to 1. The MIXER_IF_EN

bit defaults to IF mode on SPI startup and reset.

In addition, the baseband pins (I_P, I_N, Q_P, and Q_N) must

see an open load for optimum performance in IF mode.

LO INPUT PATH

The LO input path operates from 5.4 GHz to 10.25 GHz with

an LO amplitude range of −6 dBm to +6 dBm. The LO has an

internal quadrupler (×4) and a programmable band-pass filter.

The LO band-pass filter is programmable using the QUAD_

FILTERS bits (Register 0x09, Bits[3:0]). See the Performance at

Different Quad Filter Settings section for more information on

the QUAD_FILTERS settings.

The LO path can operate either differentially or single ended.

LOP and LON are the inputs to the LO path. The LO path can

switch from differential to single-ended operation by setting the

QUAD_SE_MODE bits (Register 0x09, Bits[9:6]). See the

Performance Between Differential vs. Single-Ended LO Input

section for more information. When using the LO as single

ended, the unused LO input pin must be terminated with a

50 Ω load.

Figure 81 shows a block diagram of the LO path.

AMP

4 × LON

4 × LOP

LON

LOP

×4

Figure 81. LO Path Block Diagram

Enable the quadrupler by setting the QUAD_PD bits

(Register 0x03, Bits[13:11]) to 0x0. To power down the

quadrupler, set these bits to 0x7.

SIDEBAND SUPPRESSION OPTIMIZATION

Unwanted sideband can be upconverted from the quadrature

error by generating the quadrature LO signals and the external

quadrature inputs. Deviation from ideal quadrature (that is,

total sideband rejection and no sideband tone upconverts) on

these signals limits the amount of achievable sideband rejection.

The ADMV1013 offers approximately 25° of quadrature phase

adjustment in the LO path quadrature signals to suppress the

sideband. Make these adjustments through the LOAMP_PH_

ADJ_I_FINE bits (Register 0x05, Bits[13:7]) and the LOAMP_

PH_ADJ_Q_FINE bits (Register 0x06, Bits[13:7]). These bits

reject the unwanted sideband signal. To achieve the required

sideband suppression, it may be necessary to adjust the

amplitude difference between the quadrature inputs, as well

externally.

In I/Q mode, the recommendation is to adjust the sideband

suppression through the external transceiver digital-to-analog

converter (DAC).

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