ADAR2001

Data Sheet

Rev. 0 | Page 18 of 39

TRANSMITTER STATE MACHINE

Like the multiplier/filter state machine, the transmitter state

machine can be used to quickly cycle through transmit states

without using the comparatively slower SPI interface.

To enable the state machine, set the TX_SEQ_EN bit

(Register 0x016, Bit 7) high.

The transmitter state machine controls the status of the four

PAs (sleep, ready, or active) and the status of the 1:4 splitter

network by defining the desired modes of operation in

Register 0x050 to Register 0x06F. The PAs are in sleep mode

when the ready and active bits are not enabled. Each mode

outlines a custom set of operating conditions.

Although only four states are required to cycle through a transmit

cycle by each of the PAs, a state machine depth of 70 is provided

for optimum flexibility and to lower the total number of control

lines required to operate multiple ADAR2001 chips in parallel.

It is possible to control up to 16 ADAR2001 ICs using the same

four sequencer lines (MADV, MRST, TxADV, TxRST). See the

Sequencer Control Latch Bypass section for more information.

Following the mode definitions, the user must fill the state bits

in Register 0x019 to Register 0x03B with the modes of interest.

Any state can point to any mode, except State 0 which always

points to Mode 0. Note that the sequencer moves through the

states in order, up to the state machine depth.

After the states are defined, the user must set the number of

states to be used by the sequencer by changing the TX_STATES

bits (Register 0x017, Bits[6:0]). TX_STATES is 0 indexed.

Therefore, setting the depth to 0 leaves TX_STATE_1

(Register 0x019, Bits[7:4]) as the only state in the loop.

After the transmit state machine is programmed, operation is

controlled by the TxRST (transmit reset, Pin 9) and TxADV

(transmit advance, Pin 8) pins. Alternatively, operation can be

controlled through the SPI using the TX_RST_SPI and

TX_ADV_SPI bits (Register 0x044, Bit 1 and Bit 0, respectively).

TxRST moves the pointer on the transmit state machine to

State 0 regardless of the current position of the pointer and can

be asserted at any time. State 0 always refers to Mode 0 and

cannot be set to another mode. However, Mode 0 can be

overwritten with any transmitter configuration. Mode 0 is

defined in Register 0x050 and Register 0x051.

TxADV pulses advance the transmitter state machine pointer

one state at a time until the defined sequencer depth is cycled

through. At that point, an additional TxADV pulse moves the

pointer back to State 1. State 1 applies the mode defined in the

TX_STATE_1 bits (Register 0x019, Bits[7:4]).

SINGLE-CHANNEL FREQUENCY SWEEP

Figure 29 shows a method of operation that can be used during

a 20 GHz to 40 GHz frequency sweep of Channel 1. Based on

Table 7, three multiplier/filter states are required during a 20 GHz

to 40 GHz sweep. In this example, the defined state machine depth,

MULT_STATES (Register 0x018, Bits[3:0]), is 3 because there

are four states inside the loop, and MULT_STATES is 0 indexed.

As shown in Figure 29,

•

Multiplier/Filter State 0 = sleep (outside the loop)

•

Multiplier/Filter State 1 = mid band multiplier ready

•

Multiplier/Filter State 2 = output 20 GHz to 25 GHz to PAs

•

Multiplier/Filter State 3 = output 25 GHz to 30 GHz to PAs

•

Multiplier/Filter State 4 = output 30 GHz to 40 GHz to PAs

The initial state is the sleep state where power consumption is

at a minimum. This state is reached by pulsing the MRST pin.

A pulse on MADV then advances the state machine to the first

state inside the loop, which is defined as a ready state, where

the mid band multiplier is partially powered but not active, and

the BPF is disabled to pass the higher portion of the mid band.

By using this ready state, an additional pulse on MADV makes

this subcircuit path active in less than 10 ns. By making use of

the ready mode for the upcoming state throughout the sweep,

the multiplier/filter switching and settling time can be kept less

than 10 ns between all states.

After the appropriate number of pulses is applied to MADV (5,

in this case), the state machine automatically returns to the first

state in the loop (ready).

MULT: ALL SLEEP

BPF: N/A

PA: ALL SLEEP

SLEEP

MULT_STATE_0

TX_STATE_0

MULT: MID RDY

BPF: N/A

PA: CH. 1 RDY

CHANNEL 1

READY

MULT_STATE_1

TX_STATE_1

MULT: MID ACT

BPF: HIGH

PA: CH. 1 ACT

CHANNEL 1

20GHz TO 25GHz

MULT_STATE_2

TX_STATE_2

MULT: HIGH ACT

BPF: LOW

PA: CH. 1 ACT

CHANNEL 1

25GHz TO 30GHz

MULT_STATE_3

TX_STATE_2

MULT: HIGH ACT

BPF: HIGH

PA: CH. 1 ACT

CHANNEL 1

30GHz TO 40GHz

MULT_STATE_4

TX_STATE_2

MULTIPLIER

RESET

TRANSMITTER

RESET

MULTIPLIER

ADVANCE

TRANSMITTER

ADVANCE

MULTIPLIER

ADVANCE

TRANSMITTER

ADVANCE

MULTIPLIER

ADVANCE

MULTIPLIER

ADVANCE

TRANSMITTER

ADVANCE

MULTIPLIER

ADVANCE

Figure 29. State Machine Loop Example for a Frequency Sweep from 20 GHz to 40 GHz on a Single Channel