Introduction to low power consumption and UPF

Preface

Make relevant explanations according to personal understanding of online public materials , And quote some pictures and contents for supplementary explanation , Relevant links are placed at the end of the article .

One 、 summary

IEEE1801 UPF   -- A brief introduction and overview

Unified Power Format (UPF) Used to describe  power intent（ Power supply intention ） Standards for , be based on TCL Language writing .
at present , the latest version UPF by UPF3.0 1801-2018.

Synopsys The recommended simulation involves three stages

1. Before logic synthesis RTL+UPF :
   RTL model Not inserted Low Power cells（isolation cells, level shifters......) and power and ground (PG) net.VCS NLP according to UPF Insert virtual cells and net
    
2. After logical synthesis Gate-level netlist + UPF’:
   DC After synthesis UPF’ (UPF prime), At this time, the net list is inserted isolation cells,level shifters,retention registers, but PG net and power switches Not yet .
   Simulation at this stage , need gate-level netlist,UPF’ file as well as  .db file.( .db yes binary Format , describe Cell Every Pin Direct dependence on power supply , from test Format .lib Transformed into ） Simulation at this stage is not necessary .
    

3. After physical implementation Gate-level netlist + UPF" perhaps Gate-level netlist with PG pin：
   after IC Compiler,IC Compiler II, perhaps Fusion Compiler After layout and wiring , Will produce UPF" (UPF double-prime).
   There is no need to use VCS NLP Running belt UPF" The simulation of , You can run directly PG Netlist The simulation of .
   PG Netlist contain UPF As defined in low power cells, as well as PG pin Power supply network , Can be used directly vcs Simulation .

UPF(Unified Power Format)  Unified power management format ,UPF file As Golden file, Throughout the process , Guide tool implementation .

SDC The timing constraint is Timing Spec;UPF by POWER DESIGN SPEC, Pass it to the back end as an input file , It needs to be ensured that Golden File.

Two 、Components of UPF

1. Power Domain： A set of elements in a design , They share a common set of power . By default , All logical elements in the power domain use the same primary power and primary ground .

• Every domain There is one. scope And a extent
• scope It is the logical level that this voltage domain is defined , and extent Is a set of logical elements belonging to this voltage domain .

2.Power Supply Network ： Abstract description of power distribution ( port 、 The Internet 、 Complete sets of equipment and switches )

3. Power State table： Combined state of different power domains

4. Isolation Strategies： When the main power supply of a power domain is removed , How to isolate the interface of the power domain

5. Retention Strategies (regs are retained when power down, Dubhe doed not include)

6. Level Shifter Strategies： The signal is connected to different power domains with different voltages

7. Power Switch

2.1、Power Domains

2.2、Supply Sets

• supply nets and supply ports: Every scope They all have a group supply nets and ports On a specific hierarchy .

  • supply net It is a conductor that carries the power supply voltage or grounding in a given power supply area , Across multiple voltage domains net Is defined as “reused".

  • supply port It is between two adjacent levels of the design hierarchy 、 The power connection point between the parent and child blocks of the hierarchy .

  • supply net adopt supply port From one level of the design hierarchy to the next

• supply set: It's a supply nets The abstract set of , Usually it's just one vdd A piece of gnd Of net.

  • yes domain-independent Of , stay supply set Medium power and ground Can be arbitrarily in this scope As defined in power domain Use .

• supply set handle: Give me a power domain Defined abstraction supply set.

  • By default , Each power supply domain Yes supply set handle for domain’s primary supply set, a default isolation
    supply set, and a default retention supply set.

  • supply set handle Allows you to create any power set for the power domain 、 The power network and power port are designed comprehensively .

 2.3、Simstates
       

 2.4、Power State
        

• power state table: List the allowable combinations of voltage values and power switch states of all power domains in this design .

 2.5、Power Switches
        

• power switch: It's a device , Turn on and off the power supply network . A switch has an input supply network , An output supply network , And at least one input signal for controlling the switch , It can be controlled by multiple signals , Multiple signals can also be output .

 2.6、Isolation Strategies

isolation cell: A known logic value is generated during the closing of the voltage domain .

• Connected to the closed block after , Provide a constant value output to prevent the occurrence of X state . Such as below ,block Turn it off P_UP Set as 0, Output constant 0

        

 2.7、Level Shifting Strategies

• level shifter: The level shifter converts the signal from the voltage swing of the first domain to the voltage swing of the second domain .

When signals in two different voltage domains communicate , Need to add level-shifter cell To change the level .

 2.8、Retention Strategies
       

• retention registers： In the power domain with power switch , Any register that must retain data during shutdown must be implemented as a reserved register . The reserved register has a separate 、 Always on Supply Network , Sometimes called backup power , It keeps the data in the reserved register stable when the main power supply of the domain is turned off .

 2.9、Successive Refinement of Power Intent
        

Reference resources

1、 author	post
	IEEE1801 UPF --- A brief introduction and overview
	Low power verification ( Two ）UPF, Low power process ,VCS NLP
	Lower power design & UPF Study
	Low power design —— be based on UPF Design

[UPF] low power consumption （Low Power Design）and UPF Introduce