Method and apparatus for efficient implementation of digital filter with thermometer-code-like output

Apparatus for processing a binary coded signal to generate a thermometer coded signal, comprising:

• a memory;
• and
• a processor coupled to the memory and operative to:
• (i) obtain a binary coded input signal;
• (ii) perform a binary arithmetic operation on a least significant bit (LSB) portion of the binary coded input signal;
• (iii) generate at least one signal representative of an occurrence of one of an overflow condition and an underflow condition, in response to the binary arithmetic operation performed on the LSB portion;
• (iv) shift a thermometer coded signal in response to the signal representative of the occurrence of one of the overflow condition and the underflow condition, wherein shifting of the thermometer coded signal represents one of incrementing and decrementing a most significant bit (MSB) portion of the binary coded input signal;
• and (v) output the thermometer coded signal.

Apparatus for processing a binary coded signal to generate a thermometer coded signal for use in a digital phase locked loop circuit, comprising:

• first processing logic for obtaining a binary coded input signal representative of an error;
• performing a binary arithmetic operation on a least significant bit (LSB) portion of the binary coded input signal;
• and generating at least one signal representative of an occurrence of one of an overflow condition and an underflow condition, in response to the binary arithmetic operation performed on the LSB portion;
• and
• second processing logic, coupled to the first processing logic, for shifting a thermometer coded signal in response to the signal representative of the occurrence of one of the overflow condition and the underflow condition, wherein shifting of the thermometer coded signal represents one of incrementing and decrementing a most significant bit (MSB) portion of the binary coded input signal;
• and outputting the thermometer coded signal.